I located the flag of the
District of Los Santos, in the Province of Los Santos,
Panama. It is horizontally divided in three stripes of
blue-yellow-red with "10 de Nov. de 1821" in black
letters across the yellow stripe. It can be seen at here.
About the district from wikipedia:
"Los Santos District is a district (distrito) of Los Santos
Province in Panama. The population according to the 2000 census
was 23,828. The district covers a total area of 429 kmē. The
capital lies at the city of Las Tablas. " Valentin Poposki, 14 February 2010